Data was collected by giving studen

Data was collected by giving students of Mathematics education a sequence of proving
questions. Students’ activity while doing the task (prooving the quetions) was video-typed using
handycame. Students’ work was analized and became a based interviews data. To observe and attain
the illustration of students critical thinking abilities, we implied the following steps: (1) students were
given the task to solve the proving questions. (2) The researchers examined the results of students’
work. (3) researchers provide questions related to the answers given by the students. Furthermore,
from the results of the written and verbal data (data from interviews) were collected and then
examined its provisions or it consistency. If there was data that was inconsistent, then the second
interview conducted in order to obtain the data according to the research questions.